EAGER: Unravel, mimic and control physiology via chiral-induced spin selectivity: a quantum approach

本项目旨在揭示和控制纳米尺度上的手性诱导自旋选择性效应。CIS是一种不同寻常的行为，最初是在生物结构中观察到的，后来才被用于技术应用。它描述了这样一个事实，在室温下，具有手性(或镜像)对称性的分子--例如DNA--的电子传输有利于一种称为自旋的量子属性的特定状态。这种自旋偏好有效地转化为通过手性分子的电子传输比通过非手性分子的电子传输更有效，这一性质理所当然地引起了人们的极大兴趣。对映体(相互镜像的手性分子)具有相反的电子自旋取向偏好，这可能会为药物开发提供信息；任何依赖于最佳电荷传输的技术--即整个电子行业--都可以从利用和控制顺时态效应中受益。由于蛋白质和大多数生物分子都是手性的，CIS也可能对信号传递具有巨大的生物学意义。这项研究属于新兴的“量子生物学”领域，该领域研究量子力学定律如何在生物功能中发挥作用。这项工作将推动美国第一个虚拟量子生物学中心的创建。这样的中心将成为量子生物学从业者互动、合作和向更广泛的公众传播他们的发现的自然组织结构。中心成员将揭开并批判生物学中潜在的可疑的量子效应主张，并将这一领域置于公众视野中坚实的科学基础上。该中心还将催化一些活动，如每周一次的量子生物学在线会议，这些会议已经由PI组织了一年多。手性诱导自旋选择性(CISS)描述了这样一个事实，即在室温下，通过手性分子的电荷传输有利于特定的电子自旋取向(或“自旋极化”)。由于顺式效应，对映体具有相反的电子自旋取向。这一观察结果可能具有巨大的生物学意义，因为蛋白质和大多数生物分子都是手性的。在纳米尺度上对CIS仍缺乏明确的理解。在这里，研究人员提议在纳米尺度上阐明DNA中CIS背后的机制。目前，利用化学技术(例如：电化学、I-V曲线)来研究CIS，依赖于手性纳米结构与处于“经典态”的电子自旋相互作用的系综；这分别排除了对穿过手性结构的总电荷的定量测量以及当通过这些手性分子时，“非平凡量子态”(例如，自旋叠加)中的自旋如何演化。建议的装置--ESR-STM与一个手性分子合作，该分子被注入“非平凡量子态”中的电子自旋--将克服目前的实验限制，从而使人们能够使用量子力学的语言和工具来预测和定量地理解CIS。研究人员将在不同的条件下(例如，略有不同的温度，不同的DNA长度)将DNA连接到ESR-STM的尖端，并使用磁共振技术制备任意自旋状态的电子，然后将其注入分子中。通过表征电子相干是如何通过不同的纳米手性势传输的，就有可能利用量子自由度来劫持和驱动生理和生物信号处理，并模仿数百万年来自然界开发和优化的策略来传输量子信息。该项目由生物科学中分子和细胞生物科学部分子生物物理学分部支持。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为是值得支持的。

This project aims to unveil and control the “chiral-induced spin selectivity” (CISS) effect at the nanoscale. CISS is an unusual behavior first observed in biological structures, and only later harnessed for technological applications. It describes the fact that, at room temperature, electron transport through molecules with chiral (or mirror) symmetry -- e.g., DNA -- favors particular states of a quantum property called spin. Such a spin preference effectively translates into more efficient electron transport through chiral molecules than through achiral ones, and this property has justifiably attracted significant interest. Enantiomers (chiral molecules that are mirror images of one another) have opposite electron spin orientation preferences, which could inform drug development; and any technology that relies on optimal charge transport – i.e., the entire electronics industry – could profit from harnessing and controlling CISS-like effects. CISS might also have tremendous biological implications for signaling, as proteins and most biomolecules are chiral. This research falls within the emergent field of “quantum biology” that studies how the laws of quantum mechanics might play a role in biological function. This work will foment the creation of the first US-based virtual Quantum Biology Center. Such a center will become a natural organizing structure for quantum biology practitioners to interact, collaborate and disseminate their findings to the broader public. The Center members will demystify and critique potentially dubious claims of quantum effects in biology and place this field on firm scientific ground in the public eye. The Center will also catalyze events such as weekly online meetings on quantum biology, already being organized by the PI for over a year.The chiral-induced spin selectivity (CISS) describes the fact that, at room temperature, charge transport through chiral molecules favors a particular electronic spin orientation (or ‘spin polarization’). Because of the CISS effect, enantiomers have opposite electron spin orientation preferences. This observation might have tremendous biological implications, as proteins and most biomolecules are chiral. An unambiguous understanding of CISS at the nanoscale is still lacking. Here the investigators propose to elucidate the mechanisms behind CISS in DNA at the nanoscale. Currently, CISS is studied using chemistry techniques (ex.: electrochemistry, I-V curves) relying on ensembles of chiral nanostructures interacting with electron spins in “classical states”; this precludes, respectively, quantitative measurements of total charge going through the chiral structures and of how spins in “non-trivial quantum states” (e.g., spin superpositions) evolve when transported through such chiral molecules. The proposed setup – a ESR-STM working with a single chiral molecule that gets injected with electron spins in “non-trivial quantum states” – will overcome the present experimental limitations and thus enable a predictable, quantitative understanding of CISS using the language and tools of quantum mechanics. The investigators will attach DNA under different conditions (e.g., slightly different temperatures, a variety of DNA lengths) to the tip of the ESR-STM and use magnetic resonance techniques to prepare electrons in arbitrary spin states, which will then be injected into the molecule. By characterizing how the electron coherences are transported through the different nano-chiral potentials, it becomes possible to harness quantum degrees of freedom to hijack and drive both physiology and biological signal processing, and to mimic strategies developed and optimized by nature over millions of years to transduce quantum information. This project is supported by the Molecular Biophysics Cluster of the Division of Molecular and Cellular Biosciences in Biological Sciences Directorate.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.